1. Technical Field
The present invention relates to an edge light type light source device and a display apparatus including the light source device.
2. Description of Related Art
Recently, a display apparatus such as a liquid crystal display and a liquid crystal television has been widely spread. Such the display apparatus includes: a rectangular plate-shaped display panel which has a display screen displaying an image on a front side; and a light source device which is disposed on a rear side of the display panel to emit light to the display panel. There is an edge light type light source device in which a light guide plate is disposed on the rear side of the display panel and a light source such as a light emitting diode (LED) is disposed on an end surface side of the light guide plate. In the edge light type light source device, light made incident in the end surface of the light guide plate is emitted from one surface of the light guide plate while diffusing in the light guide plate, and is made incident in the display panel.
FIG. 1 is an exploded perspective view illustrating a configuration of major components of a conventional display apparatus, and FIG. 2 is a longitudinal sectional view of the conventional display apparatus. Further, FIG. 2 illustrates only the longitudinal sectional view of a place in which a light source unit is disposed in the conventional display apparatus.
In a conventional edge light type light source device, for example, a light source unit 2 in which a light source 20 is mounted on a strip-shaped substrate 21 in a long side direction is disposed to face one end surface of a rectangular light guide plate 3. Further, the light guide plate 3 has an optical sheet 31 adhered to one surface thereof, and a reflection sheet 32 adhered to the other surface thereof. The light source unit 2 is supported by a heat spreader 9. The heat spreader 9 has a support plate 90 which supports the substrate 21 of the light source unit 2 and a protrusive plate 91 which is provided with a light guide plate pressing portion 92 abutting against the reflection sheet 32, and is formed in an L-shape.
A backlight chassis 6 (hereinafter, referred to as a BL chassis 6) has a shape in which one sidewall and a part of a bottom plate connecting to the one sidewall are cut from a dish-shape. The protrusive plate 91 of the heat spreader 9 is configured so that a protruded end thereof is engaged with an end part (a place in which the sidewall is cut) of the bottom plate of the BL chassis 6, and the heat spreader 9 and the BL chassis 6 support the light source unit 2 and the light guide plate 3 with being engaged with each other. The light source unit 2 and the light guide plate 3 supported by the heat spreader 9 and the BL chassis 6 are covered with a panel chassis 5 from the optical sheet 31 side at a peripheral edge of the light guide plate 3, and are clamped by the panel chassis 5, the heat spreader 9 and the BL chassis 6. By the above-described configuration, a light source device is achieved. In addition, with respect to the light source device having the above-described configuration, a liquid crystal panel 1 is disposed so that one surface thereof faces the light guide plate 3 (optical sheet 31), and a peripheral edge of the liquid crystal panel 1 is covered with a bezel 4 from an outside (a display screen side), to achieve a display apparatus.
In the display apparatus having the above-described configuration, as illustrated in FIG. 2 by arrows, light from the light source unit 2 is emitted to not only the light guide plate 3 but also the display screen side, etc., and the light emitted to the display screen side reaches the panel chassis 5. Generally, the panel chassis 5 is often made of a resin, and in the case of a resin product, the light reaching the panel chassis 5 is transmitted through the panel chassis 5. When the light transmitted through the panel chassis 5 passes through between the bezel 4 and the liquid crystal panel 1, light leakage occurs at the peripheral edge part of the liquid crystal panel 1. Further, when the light transmitted through the panel chassis 5 is made incident in the liquid crystal panel 1, luminance at one end part (an end part on a side in which light source unit 2 is provided) of the liquid crystal panel 1 is increased.
Japanese Patent Application Laid-Open No. 2008-91317 proposes a backlight module including a light source and a light guide plate, wherein a reflection region (a reflection surface) is provided around the light source, in order to allow the light from the light source to be efficiently made incident in a light incident surface of the light guide plate.